There exist various procedures of making direct communications between terminals under a wireless base station or directly starting or stopping the communications between the terminals.
For example, a wireless LAN system based on IEEE 802.11 (ISO/IEC 8802-02-11:1999 (E) ANSI/IEEE Std 802.11, 1999 edition) is known as a wireless LAN. A group executing additive corrections associated with QoS (Quality of Service) has considered a wireless LAN system for making direct communications between terminals under a wireless base station and the procedure of setting up (starting) or tearing down (stopping) the direct communications between the terminals in the system concerned.
Furthermore, in the case of Japanese digital codeless telephones (Personal Handyphone System:PHS), the direct communication mode between terminals can be used in addition to the communication mode via wireless base station between terminals.
The wireless communication system in which a wireless terminal communicates with a wireless base station or directly communicates with another wireless terminal does not have any method of actually estimating and judging whether the wireless terminal is under such a communication condition that direct communication can be performed between terminals under the initiative of the wireless base station or the communication condition is better than that of the communication via the wireless base station.
Accordingly, there actually frequently occurs such a situation that even when direct communication is started between wireless terminals under the initiative of the wireless base station, the direct communication is actually improper, and the efficiency is low.
Furthermore, the wireless base station does not have any method of judging whether the communication condition falls into an improper condition to the direct communication between wireless terminals after the direct communication is held, and there is only a method of tearing down the direct communication on the basis of the judgment at the wireless terminal side.
In order to detect a partner wireless terminal with which the wireless terminal concerned makes direct communication under the initiative of the wireless terminal or a partner wireless terminal with which it is better for the wireless terminal concerned to directly communicate than the communication via the wireless base station or make a judgment as to whether the direct communication is ceased and the communication is switched to the communication via the wireless base station, the processing load at the wireless terminal side should increase, and the power consumption and construction scale of the wireless terminal should increase.
Furthermore, in the procedure of starting the direct communication, when the direct communication is started under the initiative of the wireless terminal and through the wireless base station, the frame exchange amount required for the starting procedure is larger than the communication under the initiative of the wireless base station by the amount corresponding to the start request frame from the wireless terminal. Likewise, in the procedure of stopping the direct communication, when the direct communication is stopped under the initiative of the wireless terminal and through the wireless base station, the frame exchange amount required for the stopping procedure is larger than the communication under the initiative of the wireless base station by the amount corresponding to the stop request frame from the wireless terminal.
In addition, no consideration has been made concerning the judgment as to the setup or teardown of the direct communication on the basis of information on the direction of a directional beam under the initiative of the wireless base station in the use style that the wireless base station uses directional beams for communications between wireless terminals.
Furthermore, when the direct communication is started through the intervention of the wireless base station, no consideration has been made in the case where the directional beam directed to the wireless terminal is used, and the information concerning the direction of the directional beam has not been used. Furthermore, there has not been any method of specifically using the information of the reception frame from the wireless terminal when the wireless base station intervenes.
Therefore, the present invention has an object to provide a judgment of starting the direct communication between wireless terminals at a wireless base station and also a judgment of starting the direct communications between wireless terminals at a wireless terminal when the above situations exist.